Cutinase is a multifunctional enzyme that belongs to the family of serine esterase. It can not only hydrolyze long- and short-chain fatty acid esters, emulsified triglycerides and soluble synthetic esters, but also participate in esterification, transesterification etc. By virtue of its special structure, cutinase can also hydrolyze cutin. Therefore, cutinase finds wide application in a variety of industries, including textile, food, biocatalysis and chemical industries.
Researches on the fermentation of cutinase are mainly focused on optimization of culturing conditions of wild microorganism strains and highly efficient expression of recombinant fungal cutinase using different genetically engineered host cells (such as Saccharomyces cerevisiae, E. coli, and Aspergillus spp.), aiming to optimize production processes and reducing production cost, among others. However, so far no reports are available on the industrialized production of cutinase, due to the problems of high cost of cultivation and long period of growth of yeasts, as well as poor stability of F. solani pisi, a recombinant strain for producing cutinase.
Cheng Sheng from our laboratory reported (Chen S, Tong X, Woodard R W, Du G C, Wu J, Chen J, Identification and Characterization of Bacterial Cutinase, The Journal of Biological Chemistry, 2008, 283 (28) 25854-25862) cutinase from Thermobifida fusca which showed a good thermal stability, a wide pH stability range, an optimal temperature of 60° C., and an optimal pH of 8.0, consistent with the requirements of application of cutinase for textile use. Based on this, optimization of fermentation was conducted, achieving an enzyme activity of 500 U/mL in a fermentation run in a 3 L fermentor for 30 hours (Chinese Patent Application No. 200910259651.1 to Jing Wu, Dan Wu, Yao Zhang, Jian Chen, and Sheng Chen, titled “A Fermentation Process of Recombinant Cutinase”). However, two disadvantages remain. Firstly, supplementation on the basis of complex media resulted in complexity of the components and inconvenience in the control of fermentation process. Secondly, use of the type II secretion pathway to transport across the outer and inner membranes of E. coli in two steps yielded low efficiency of transport, while addition of a certain amount of glycine during fermentation to modify the permeability of cell wall in order to increase the level of extracellular secretion lead to increased production cost.